Tuesday, November 27, 2012

How to Build A Power Suit and/or Powered Armor, Part 2: Physical Augmentation

Alrighty!  So, we know what we're looking for in a power suit, and we know what the market has available right now.  So let's drill down the basics of physical augmentation, how companies are accomplishing this now, and possible alternatives for the future, and for the home hobbyist.

What do we mean when we say "physical augmentation?"  The first thing that comes to my mind, personally, is strength amplification.  Enabling a person that can normally lift, say, 250 pounds, to lift something more like 500 pounds when wearing the suit.  Now, most likely due to the nature of mechanics this would be a linear strength amplification, that is, the suit is capable of exerting a certain amount of power(in this case, 250 pounds), so if the same person could lift 400 pounds normally, the suit would bump them up to 650.  Multiplicative would be bumping it to 800, but it's mechanically very difficult to do this.  That said, adding an extra 250 to your bench press is amazing in itself, so we won't knock it.

The main goal of modern power suits thus far, however, has been focused mainly on endurance.  This is for several reasons, the biggest of which is that we don't necessarily need soldiers in the field to be physically stronger, but we need them to be able to go longer with a moderately increased payload.  More gear and endurance means better rested soldiers with more equipment at their disposal.  This should not be brushed off, as Samus Aran or Master Chief would be in a bad way if, by the time they got to their destination, they were too pooped to fight.

Another element of physical augmentation is speed, maneuverability, and reaction time.  Increase your leg strength, and you should be able to run faster and jump higher, theoretically.  In order to stick to this idea with a powersuit, however, you need to maintain a good power to weight ratio.  A power suit that put an extra 100 pounds of strength into your legs but weight 80 pounds itself isn't going to have that visible an effect.  Conversely, if you can get the suit to put an extra 250 pounds of force into your legs, and it only weighs 80 pounds, well, you're gonna see a hell of a difference there.  The other side of this is that you need speed in the exertion of this power.  It's not going to do much for your vertical if you can put out that extra force, but only at a low velocity.

So where do we go here?  The first thing any power suit is going to need is an exoskeleton.  This is the framework you attach your mechanical muscles to, much like your own skeleton.  Two major things need to be considered in the exoskeleton.  Firstly, there's the issue of materials.  You want your frame to be lightweight, but also strong.  It's going to be taking a lot of angular forces.  If you're on a budget, your options are probably steel stock for a nice sturdy frame, or, for less sturdy but more lightweight, aluminum stock.  The nice thing about these options are that they're cheap, plentiful, and easy to work.  Steel is quite easily weldable, if you have such skills, and both are easily machined in the home.  Titanium is your third option, offering superior strength to aluminum, without as much weight at steel.  One inch diameter, bar stock for aluminum, titanium, and stainless steel weighs about 1 pound, 1 1/2 pounds, or 2 1/2 pounds per foot, respectively.  Titanium is stronger on a pound-for-pound basis than aluminum or steel, however it is a pain in the ass to work with, especially in a home environment.  Stainless steel is strong, but heavy.  I would honestly say our biggest contender here is aluminum.  It's relatively easy to machine and work with, available enough for the home consumer, and not prohibitively expensive.

Now we come to our second issue: joints.  Knee and elbow joints are easy enough to take care of, they only go one way.  Shoulder and hip joints, however, are a pain in the ass.  Because of the way they function, the best place for the mechanisms for the joint to be located are, unfortunately, inside your shoulder and hip.  This, obviously, is not an option.  Because of this, you're probably going to have to build the exoskeleton rather far off the body if you want full range of motion at these joints(see the XOS that we discussed in the previous post).  Or, you can be creative, and try to come up with a new way of articulating these joints while still keeping the framework close to the body.  Which brings us to our next hurdle...

Force generation.

How do we exert the power?  Currently, all major manufacturers are utilizing powerful servo motors.  These are similar to the motors you see in remote-control toys.  Typically electric-powered, these motors activate on the major joins in the exoskeleton, driven by a computer processing the input from your body.  They have their drawbacks, though.  First of all, they are quite expensive.  Second of all, they tend to be power-hungry, and third of all, they are rather poor at mimicking "real" organic movement.  You can see this in the awkward slowness in the XOS' punching movements in the demo video.

So what other options do we have?  There is hydraulics and pneumatics, firstly.  Both of these are closer to mimicking the actual mechanics of muscles, however they have the drawback of being rather large and clunky, as well as typically being either rather slow(hydraulics), or requiring charging time with each use(pneumatics).  Also, they tend to be rather binary, especially in the case of pneumatics(that is, they're more of an on-or-off kind of thing).  This is not always the case, however, and I think, especially for the home hobbyist, that hydraulics could be an option.  Basically you strap the parts for a lift  gate or forkift on your arms and, goshdarnit, you can lift hundreds of pounds!  Rather slowly, but still, the power function is there.

Finally, there is the fringe, future-tech kind of stuff.  Electro-active polymers are currently being investigated for the purpose of artificial muscles.  EAPs are materials that contract when an electrical current passes through them(similar to our own muscles).  It is a burgeoning field that holds promise, but the concrete stuff exists mostly on the academic level.  That said, the guy that discovered them back in the 1800s did so just by running an electric current through a rubber band, so home experimentation is a possibility.  If you feel like being intrepid, take a look into this!

There's also pneumatic artificial muscles.  These are nifty, and different from traditional hard-tube pneumatics in that they operate with flexible air-filled bladders.  These look very promising as well, however you still need to conquer the air compression hurdle.  Also, to operate in any kind of non-air situation(like underwater, or in a vacuum), you'd need to carry your own air tanks with you in addition to your compressor, adding to your weight requirements.

So, all this said and done, let's look at our possible options this far, going from cheap, junkyard robot, to futuristic space warrior.

Option 1:
Frame: Stainless Steel Exoskeleton
Joints: Mechanical hinges, no ball joint actuation at shoulders and hips
Force: Hydraulic muscles
Comments: The junkyard special!  You're probably not going to get anywhere very quickly, and you're going to have a limited range of motion, but hey, you can probably lift a car!  You can also probably construct most of this with a good solid base knowledge of welding and hydraulics.
Cost: $500-1000 (not including cost of the computer driving the mechanics)

Option 2:
Frame: Aircraft Aluminum Exoskeleton
Joints: Mechanical hinges at elbows and knees, ball joint actuators at shoulders and hips.
Force: Industrial Servos or Pneumatic Air Muscles
Comments: The home hobbyist with some money to burn!  You'll get pretty damn good range of motion out of this(assuming your computing is good), and have solid power output as well.  If you can figure out good joint mechanics for your ankles, then you can probably add to your sprinting and vertical, as well.  Drawback is the issue with servo motors stated above, or the annoying "whooshing" sound you'll make every time you move if you use pneumatics.
Cost: $2500-10,000

Option 3:
Frame: Titanium-aluminum alloy, with carbon fiber reinforcement.
Joints: Mechanical hinges at elbows and knees, external ball joint mechanics at shoulders and hips to keep the exoskeleton close to the body.
Force: Elector-activated polymer muscles attached to carbon fiber tendons.
Comments: The space-warrior!  I'm not even sure if this thing is theoretically possible currently(probably not).  EAPs are still too experimental and have too short a range to really be considered for combat application yet.  That said, if you could build this sucker, it's probably as close to video-game canon as you can get.  Definitely something to shoot for!  If you really want to work on something like this, you should probably look into getting a degree in robotics and going to work for Northrop-Grumman or something like that.
Cost: $50,000-??????

Okay, so that's a good start to our theory-crafting!  I hope I gave you all some good starting points in your research.  Tomorrow we're going to look at the computing system for our power suit, as well as sensory driven systems and maybe some other nifty stuff.  If you guys are really serious about getting into this kind of thing, I'd recommend looking into Lego Mindstorms.  It's a relatively cheap and easy-to-work-with robotics system, and holy crap, you can do some cool stuff with it.  If you can build a lego arm that reacts in real-time to your own arm with some sensors strapped onto it, I'd say you're well on your way to a promising career in exoskeleton manufacturing.  =P

See you tomorrow!  And don't forget to go "like" the facebook page!  Twelve more likes and we get a bonus character post on the weekend!

Dan "DaRatmastah" Wallace

No comments:

Post a Comment